Metal vapor lamp



March 8, 1938. H. c. RENTSCHLER ET AL 2,110,609

METAL VAPOR LAMP Filed Aug. 50, 1935 2 Sheets-Sheet 1 INVENTOR HJC.FEW/25671767? BY HENRY ATTORN%I METAL VAPOR LAMP 2 sheets sheet 2 FiledAug. 50, 1933 INVENTOR H. C. FENI'JCHLEF BY .0. E. HENRY ATTORN%Patented Mar. 8,- 1938 UNITED STATES PATENT OFFICE METAL VAPOR LAMPApplication August 30, 1933, Serial No. 687,391

16 Claims.

This invention relates to electric discharge devices the gaseousatmosphere of which comprises metal vapor. More particularly theinvention is concerned with a novel electric discharge device 8 of thealkali metal type which finds practical application as an illuminatingmeans.

An object of our invention is to provide a novel electric dischargedevice or relatively simple design and which may be readilymanufactured.

A further object of our invention is the provision of an improvedelectric discharge device which may be readily and inexpensivelyconstructed and which may be transported without great danger ofbreaking.

A still further object of our invention is to provide an improvedelectric discharge lamp of the metal vapor type, which has improvedelectrical and physical characteristics.

Another object of our invention is to provide an electric dischargedevice which may be operated at a lower temperature than devices of thesame type heretofore proposed.

Other objects and advantages of our invention will be readily apparentfrom the following description and drawings wherein,

Figure 1 represents a view in elevation, with some of the parts brokenaway and others in section, of an electric discharge device embodyingour invention.

Figure 2 representsa view in elevation, with some of the parts insection, of an electric discharge device embodying our invention andbeing a modification of the structure shown in Figure 1.

Figure 3 represents another modification of the construction illustratedin Figure 1.

One embodiment of our invention, as shown in Figure 1, comprises anelongated envelope I0 composed of glass such as a boro-silicateglassthat is resistant to sodium vapor. The envelope has a plurality ofoutwardly extending oppositely disposed presses II and I2 locatedexteriorly of the space enclosed by the envelope. Forming a hermeticseal with the respective presses II and I2 are leading-in conductors l3and I4 which extend interiorly and exteriorly of said envelope Ill.

The conductor l3, sealed in said press II, is

rigid and has .the interiorly disposed portion thereof extending througha central opening in an insulating plug l5 composed of isolantite or thelike and having a shoulder. This plug l5 rests upon an enlarged sectionIt of the rod l3 located intermediate its ends. A hollow tubular nickelelement ll, serving as one of the electrodes,

has one of its ends closely surrounding the re cessed portion of theplug l5 and rests upon the shoulder thereof. The nickel cylinder isuncoated at its ends which represent about one quarter of the lengththereof, but the section intermediate said lengths is coated with one or5 more of the oxides or carbonates of calcium, barium and strontium,which have good electron emitting properties. An L shaped rigidconductor l 8 has the long arm thereof welded to the cylinder ll atthose portions thereof that are unw coated and the short arm is weldedto the rigid conductor l3 below the enlarged portion I6.

Another insulating plug l9, similar in all respects to the plug I5, hasthe recessed portion thereof extending into the upper end of thecylinder l I and its shoulder rests upon the upper edge of saidcylinder. A rigid conductor 20 extends through the central opening inthe plug I9 and has its inner end welded to a helical heater filament 2|adapted upon incandescence to heat the 20 electron emitting substance onthe cylinder I! to the proper temperature so that a suflicient electronemission may be provided. The lower end of the filament 2| composed oftungsten or the like is welded to that end of the conductor I3 28located above the plug l5. I

That portion of the conductor l4 extending within the envelope I0 isrigid and a section thereof extends through a central opening in a plug22, similar to the plugs l5 and IS. A nickel cyl- 30 inder 23 similar inall respects to the cylinder l1 5 has its upper edge resting against theshoulder of the plug 22. Like the other electrode H, the electrode 23has its ends uncoated, but the intermediate portion thereof coated withan electron 35 emitting material as hereinbefore described, The lowerend of the cylinder 23 has a plug 24, similar to the plug 22, forclosing the same. That section of the leading-in and supportingconductor M has an enlarged section 25 just outside 40 of the plug 22 toprevent the plug from sliding down to the end of the envelope. Aninverted L shaped conductor 26 has its long arm welded to the uncoatedsections of the electrode 23 and its short arm Welded to the rod M. TheL shaped rods l8 and 26 keep the electrodes from sliding along thelength of the envelope l0 and the stops or enlarged sections provide ameans which, together with the arms l8 and 26, maintain the electrodesin position. ll

The conductor 20 has its upper end extending through the central openingin the plug 24. To the endsof the conductors l4 and 20 located in thecylinder 23 is welded a coiled filament heater el ment, similar to theheater 2| and not shown. 66

An insulating sleeve 21 composed of isolantite or the like surroundsthat portion of the rod 20 located between the plugs I9 and 24 so thatno appreciable discharge may take place along its length. Its ends abutthe opposing faces of the plugs I9 and 24 to maintain them in positionagainst the electrodes I1 and 23. 4

The envelope I0 contains a rare gas such as helium, argon or neon. Whenargon is employed we prefer that it shall be at a pressure of about 0.2mm. of mercury. Also in said envelope is a sufficient quantity of metal,such as zinc, cadmium, sodium, caesium, rubidium or the like. In thecourse of our experimentations with lamps of this character we havefound that when the interior of said envelope I0 is highly evacuated andcontains only sodium or the like that the temperature of the bulb had tobe above 235 C. in order that a glow discharge might be maintained. Thiswas true for voltages between 15 and 115 volts. But when a rare gas,,such as argon at 0.2 mm. of mercury pressure, was also present in theaforesaid free sodium containing envelope, the glow discharge did notdisappear even at a temperature as low as 150 C. with impressed voltagesof 20 to 60 or more volts.

vided a rare gas such as argon, helium, or neon in a sodium vapor lamp,such as that disclosed by Arthur Compton in his Patent 1,830,312,-issued to him on November 3, 1931 and in, addition we are the first tohave realized the effect of a rare gas in an alkali metal lamp.

In order that the lamp may efficiently operate, we provide an enclosingenvelope 30 composed of an infra-red absorbing transparent glass. Oneend of the envelope is in the form of a short outwardly extending stem3I having an-outwardly extending press 32 at one end thereof in whichthe supporting and current carrying conductor I4 is hermetically sealed.That portion of the conductor I4 between the press I3 and the press 3Iis in the form of a helical coil I4 whose diameter is just slightly lessthan that of the stem 3I. The coil I4 serves to conduct electricity, tosupport the envelope III, to allow for expansion and contraction of thestructure within the envelope 30, and to take up shocks for theprevention of tube breakage.

The other end of the envelope has a reentrant stem 33 with a press 34 atits end. Sealed in said press 34"at about the center thereof is a rigidleading-in conductor 35 extending exteriorly and interiorly of saidenvelope. That portion of the conductor 35 within the envelope may actas a support like the conductor I4 and is welded to the conductor I3.Cemented to the outwardly extending press I I is an insulator bushing36. A ring shaped insulator 37 having a plurality of rigid rods 38firmly embedded therein closely surrounds the insulator 36. The freeends of these rods are sealed in said press for mechanical sup port, Thering, rods and bushing cooperate to minimize vibration of the envelopeIII.

As shown the inner tube is so mounted in said envelope 30 that it isappropriately and centrally spaced from the side walls thereof. Thepresses I I and I2 of the envelope I0 and those of the envelope 30 areall in line. The conductors I3 and I4 serve as supporting and electricalconducting means.

By having single leads l3 and I4 at each end of the envelope, theelectrodes may be placed near the ends of said envelope to avoid coldspots therein. In addition by having the electrod s As far as we areaware, we are thefirst to have pro-' symmetrically disposed as shown,the bulb l II is at uniform temperature.

Another embodiment of our invention is shown in Figure 2 and may besubstituted for its broadly corresponding structure disclosed inFigure 1. The discharge device comprises an elongated envelope 40composed of a sodium vapor resistant glass. Presses 4| and 42 extendingoutwardly from the envelope have respective rigid leadingin andsupporting conductors 43 and 44 sealed in said presses 4| and 42 andextending interiorly and exteriorly of said envelope. Secured to saidconductors 43 and 44 within, and near the ends of, the envelope arerespective angle rods or supports 45 and 46welded to the respectiveconductors 43 and 44 and to respective short cylindrical molybdenumplates 41 and 48 that serve as anodes. These anodes 41 and 48 areconcentric with the rods 43 and 44. An indirectly heated cathode ismounted in the center of said envelope. It comprises an elongated nickelcylinder 49 having its end portions uncoated and the portionbetween'said end portions coated with an electron emitting material,such as oxides or carbonates of calcium, strontium and barium. At

each end of said cylinder 49 is located an insulator plug 50 similar tothe insulating plugs vhereinbefore described.

Two filamentary heater elements 5| and 52 of the'same resistance arelocated in-said cylinder and in'electrical series relation, with theouter ends of said elements welded to the portions of the conductors 43and 44 located within said cylinder andiextending through the centralopenings in said insulators. A conductor 53 is welded to the electricalconnector between the two resistances 5| and 52 and tothe cylinder 49 atp the anodes and the cathode and so that the cathodev may be maintainedin proper position, an insulator sleeve 54 0f isolantite or the likesurrounds each of the conductors 43 and 44,'with the extremities thereofbearing against the end plugs 50 and-the angle rods 45 and 46. Theenvelope contains an alkali metal, such as sodium and a quantity of arare gas such as argon, neon or helium. This construction is simple andhas the further advantage that there are no cold pockets present. Thedischarge current which with alternating current will be from the coatedcylinder 49 first to one, and then to the other of the anodes, must passthrough one of the heater coils, thus assisting in heating the electronemitting material and further in maintaining the proper temperaturewithin the device.

Still another embodiment of our invention is illustrated in Figure 3 andcomprises a substantially spherical envelope composed of a sodiumresistant glass and having located therein an electrode structureexactly the same as that illustrated in Figure 1 and hereinbeforedescribed. By having the envelope spherical and by locating theelectrodes substantially along a diameter thereof, with each electrodelocated near one end of the envelope, we are enabled to eliminate coldpockets and provide a device having a uniform temperature distributionalong the surface of said envelope.

Also located in said envelope is a quantity of rare gas and a metal ashereinbefore set forth in the description of Figure 1. At diametricallyopposed points .in said envelope are short outwardly extending stems GIand 62 having presses 68 and 64 at their outer ends. Sealed in saidpresses are the respective conductors i3 and I4. Surrounding saidenvelope 60 is an envelope 65 of exactly the same construction andcomposition as the envelope 30. A plurality of conductors 86 and 61extending exteriorly and interiorly of said envelope are sealed'in thepress 34. The conductor 66 is welded to theconductor l3 and theconductor 61 extends upwardly along the we prefer to weld the rod 68 tothe crosspart of the conductor 61 and to seal the same in the press 32.

The invention is to be limited not to the exact construction shown, butonly by the prior art.

We claim:

1. An electric discharge device comprising a container, a gaseousatmosphere therein comprising a condensible gas, a stem in the wall ofthe container outside of the space enclosed by the container, anenvelope for the container provided with a reentrant stem opposed tosaid container stem, electrodes in said container, and electrode leadssealed in said stems for supporting said container and conductingelectric current thereto.

2. An electric discharge device comprising an envelope, a gaseousatmosphere therein comprising a condensible' gas, said envelope having apress outside the space enclosed by said envelope, an envelope for saidfirst mentioned envelope, said second mentioned envelope having areentrant stem, said stem having a press, electrodes in said firstmentioned envelope, and means sealed in said presses for supporting saidfirst mentioned envelope.

3. An electric discharge device comprising an envelope, electronemitting means and a gaseous atmosphere comprising a condensible gastherein, an envelope surrounding and spaced from said first mentionedenvelope, a plurality of supporting means sealed to said secondmentioned onvelope, said supporting means sealed to said first mentionedenvelope outside of the space enclosed by said first mentioned envelope.

4. An electric discharge device comprising an envelope, electronemitting means and a gaseous atmosphere comprising a condensible gastherein, an envelope surrounding and spaced from said firstmentionedenvelope, said second mentioned envelope having a reentrantstem including a press, a plurality of supports sealed in said press,means exteriorly of the space enclosed by said envelope cooperating withsaid first mentioned supports for maintaining said first mentionedenvelope in position.

5. An electric discharge device comprising an envelope, a gaseousatmosphere and an electron emitting means therein, a second envelopesurrounding said first mentioned envelope, electrical conducting meanssealed to said second mentioned envelope, said conducting means sealedto said first mentioned envelope outside of the space enclosed by saidfirst mentioned envelope, said conducting means being electricallyconnected to said electron emitting means.

6. An electric discharge device comprising an envelope, a gaseousatmosphere and an electron emitting means therein, an envelopesurrounding said first mentioned envelope, said second mentionedenvelope having a reentrant stem including a press, current conductorssealed in said press, said conductors sealed in said first mentionedenvelope exteriorly of the space enclosed by. said first mentionedenvelope.

8. An electric discharge device comprising an envelope, the atmospheretherein comprisinga condensible gas, and an electron emitting meanstherein, said envelope having 'a plurality of presses, supports sealedin'said presses, an envelope surrounding said first mentioned envelopeand also having presses, said supports being sealed also in said secondmentioned presses.

9. An electric discharge device comprising an envelope, an alkali metaland an electron emitting means therein, said envelope having a pluralityof presses extending outwardly from the space enclosed by said envelope,an envelope surrounding said first mentioned envelope and also havingpresses, said supports being sealed in said second mentioned presses andcooperating with said first mentioned press for maintaining said firstmentioned envelope in position.

10. An electric discharge device comprising an elongated envelope, asupport sealed in each end of said envelope, a plurality of indirectlyheated electrodes in line and located near the ends of said envelope, anenvelope spaced from and surrounding said first mentioned envelope, saidsupports being sealed in said second mentioned envelope at the endsthereof.

11. An electric discharge device comprising an envelope, an alkali metaland a plurality of electrodes therein, said electrodes being in line, aplurality of supports for said electrodes, said sup ports sealed in saidenvelope exteriorly of the space enclosed by said envelope, an envelopesurrounding and spaced from said first mentioned envelope, said supportssealed in said second mentioned envelope and connected to said firstmentioned envelope, one of said supports including mechanical expansionand contraction means.

12. An electric discharge device comprising an envelope, an anodelocated at each end of said envelope and a cathode located intermediatesaid anodes, said cathode comprising a plurality of heater elements inelectrical series, a thermionically active element surrounding the same,

I said elements being electrically connected to said thermionicallyactive element.

13. An electric discharge device comprising an inner envelope, a supportsealed in each end thereof, an alkali metal discharge environment and aplurality of axially alined hollow cylindrical electrodes indirectlyheated by means housed therein, a quantity of rare gas also within saidenvelope for rendering the device operative at comparatively lowtemperatures, and an outer envelope holding said inner envelope inspaced relation by means of said supports.

14. An electric discharge device comprising an envelope, a supportsealed in each end thereof,

an alkali metal discharge environment and a plurality of hollowcylindrical electrodes therein and heated by filaments housed thereby,argon at a pressure of about 0.2 mm. of mercury also within saidenvelope for lowering the temperature at of said envelope and serving tosupport the latter.

16. An electric discharge device comprising an elongated envelope, arare gas at reduced pressure sealed therein, sufficient alkali metal disposed in said envelope to take part in the discharge, a pair orelectrodes in said envelope, axially alined with one another, and eachdisposed adjacent an end of said envelope, 9. larger envelope enclosingsaid first mentioned envelope for heat insulating purposes, andleading-in conductors extending through said larger envelope and endportions of said elongated envelope and serving to support the latter.

HARVEY CLAYTON RENTSCHLER.

DONALD E. HENRY.

